JP2004162346A

JP2004162346A - Pile head connection structure of prefabricated pile

Info

Publication number: JP2004162346A
Application number: JP2002328602A
Authority: JP
Inventors: Masato Watanabe; 正登渡辺
Original assignee: Mitani Sekisan Co Ltd
Current assignee: Mitani Sekisan Co Ltd
Priority date: 2002-11-12
Filing date: 2002-11-12
Publication date: 2004-06-10
Anticipated expiration: 2022-11-12
Also published as: JP4154492B2

Abstract

<P>PROBLEM TO BE SOLVED: To considerably reduce the number of reinforcing bars in use to reduce costs, to shorten a construction period and to miniaturize a foundation by rationalizing the adjacent spacing of the reinforcing bars projected from a prefabricated pile. <P>SOLUTION: The reinforcing bars (length L) 8 are inserted and fixed into through holes 4 bored along the circumference of a diameter D<SB>2</SB>on the outer peripheral side of a base 1 of disc shape with an inner periphery D<SB>o</SB>(=D<SB>oo</SB>) and an outer periphery D<SB>1</SB>to constitute a pile head reinforcing implement 10. The diameter D<SB>2</SB>is formed as a sufficiently large diameter compared with the outer diameter D<SB>11</SB>of the prefabricated pile 12. The pile head part 13 is exposed to the ground, and the prefabricated pile 12 (the inner diameter D<SB>oo</SB>and outer diameter D<SB>11</SB>) are sunk. The pile head reinforcing implement 10 with the reinforcing bars 8, 8 projected upward is put over an upper end plate 14 of the prefabricated pile 12. The through holes 6 on the inner peripheral side of the base 1 are communicated with screw holes of the upper end plate 14, and bolts are screwed and bound to fix the pile head reinforcing implement to the prefabricated pile 12, thus forming pile head connection structure. The adjacent reinforcing bars 8, 8 are arranged at a space D<SB>6</SB>. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
この発明は、既製杭の杭頭部と建造物の下端部としての基礎とを結合する既製杭の杭頭結合構造に関する。既製杭の杭頭と基礎との接合構造を簡素化し、現場の接合作業も簡略化すると共に、杭頭の接合強度を低下させず、強化できるものである。従って、最近実施されつつある杭基礎で、従来より高品質ソイルセメント層あるいは根固め部等で従来より拡径部を造成することにより、１杭基礎当りの耐荷重が従来より２倍近く向上した高支持力のコンクリート杭を使用した杭基礎においては、基礎に要求される曲げモーメントの強度も大きいため特に効果がある。
【０００２】
【従来の技術】
従来の基礎では、一般的には、既製杭の上端板を外し、上端部のコンクリートを崩して軸鉄筋を露出させ、軸鉄筋に、基礎に配筋される鉄筋を溶接していた。また、補強鉄筋として既製杭の杭頭部の中空部に鉄筋篭の下部を挿入しコンクトトを充填し固定する構造が成されていた（特許文献１に記載の従来例。特許文献１の図７、図８。非特許文献１）。
【０００３】
そこで、円筒下篭状の接合筋で既製杭の杭頭部を囲み、あるいは、杭頭部に接合筋を溶接して取付けて地中に建て込み、構造物躯体（基礎）を構築する構造が提案されている（特許文献１）。
【０００４】
【特許文献１】
特開平１１−２１９１５号
【０００５】
【非特許文献１】
「杭基礎の調査・設計から施工まで」，第２回改訂版，土質工学会，平成５年５月２５日，２１４〜２２０頁
【０００６】
【発明が解決しようとする課題】
最近、杭１本当りの耐荷重が改善され、特にコンクリート製の既製杭において従来の杭径当り２倍程度の高支持力が得られ実用化されており、基礎と基礎杭との接合強度（曲げモーメント）を増して、建造物全体としての強度の増加を図ることが求められていた。
【０００７】
この場合、前記従来の技術では、鉄筋のかぶりを確保する観点から隣接する鉄筋の本数を増やすことに限界があり、また、鉄筋の太さを太くした場合には、１本の重量が重くなり、運搬等取扱いが面倒であると共に、現場溶接作業においても鉄筋の保持、所定強度を得る現場溶接作業自体が困難になる問題点があった。
【０００８】
また、前記鉄筋の制限下においては、基礎用のコンクリートも、通常の建築構造物の躯体に使用するものより強度が高い特殊なコンクリートを採用しなればならない問題点があった。
【０００９】
即ち、前記従来技術には、以下のような問題点があった。
（１）杭基礎の杭頭部において、基礎コンクリート内での接合鉄筋の配置間隔が狭く、コンクリート及び接合（定着）筋それぞれの強度が充分生かされていないため、コンクリートと接合（定着）筋との一体性が良くなかった。このため、使用材料強度の割に基礎としての曲げ強度が低かった。基礎において、コンクリート中での接合筋の配置（配筋）間隔が接近し過ぎており、コンクリート強度と接合（定着）筋の強度のバランスが悪く接合部の曲げモーメントの増強が限られていた。
（２）接合（定着）筋と杭頭の接合作業が複雑で経験が必要であるので、接合品質の安定性および接合作業者の習熟性の維持・管理が面倒であった。
（３）（１）（２）の要因が絡んで、基礎杭及び基礎コンクリートを造成するために、資材コスト及び作業コストが掛かり、更に溶接点数が多い場合には溶接作業がが天候に左右されるので、更に作業日数の短縮を妨げる要因の一つになっていた。
【００１０】
【課題を解決するための手段】
然るにこの発明では、杭外径より大径の円周状に補強鉄筋を突設した杭頭補強具を、既製杭の杭端板に固定したので、前記問題点を解決した。
【００１１】
即ちこの発明は、杭頭部を露出させた既製杭の上端板に、杭頭補強具の基部を固定してなる構造であって、前記既製杭の中空部に連通する開口を有する基部に、前記既製杭の外径より大径の位置で補強鉄筋を突設して、前記杭頭補強具を構成したことを特徴とする既製杭の杭頭結合構造である。
【００１２】
また、前記において、外周を既製杭の外径より大径とし、内周を前記既製杭の内径と略同一とした開口を有するドーナツ状の基部を形成し、該基部の外周に沿って、補強鉄筋を上方に向けて並列して突設して杭頭補強具を構成し、前記基部に形成した透孔と前記既製杭の上端板の螺孔とを使用して前記基部と既製杭とを固定したことを特徴とする杭頭結合構造である。また、既製杭の外径より大径の外径を有する上筒に、前記既製杭の内周と略同一とした開口を有する底板を形成して、基部とし、前記上筒の側面に補強鉄筋を上方に向けて並列して突設して、杭頭補強具を構成したことを特徴とする杭頭補強構造である。
【００１３】
更に、前記において、基部に形成した透孔と既製杭の上端板に形成されている螺孔とを使用して、前記杭頭補強具と前記既製杭とを固定したことを特徴とする杭頭補強構造である。
【００１４】
【発明の実施の形態】
（１）杭頭部１３を地上に露出させて、既製杭１２を沈設する。既製杭１２の上端板１４に、補強鉄筋８、８を上方に向けて突設した杭頭補強具１０を固定する（図２）。補強鉄筋８、８は、径Ｄ_２の円周に沿って、杭頭補強具１０の基板１に固定されている（図１）。基板１は、既製杭１２の上端板１４にボルト１９、１９で固定されている。補強鉄筋８を並列した円周の径Ｄ_２は、基板１の外径Ｄ_１を大きくすれば、既製杭１２の外径Ｄ_１１に比して十分大きな径Ｄ_２で形成できる。
【００１５】
（２）既製杭１２（外径Ｄ_１１＝７００ｍｍ）を、拡底根固め部１１００φを形成した杭穴３１内に沈設した場合であって、２０Ｎ／ｍｍ^２程度の先端支持力を確保した基礎杭を構築できる。この場合で、拡底根固め部の高支持力に対応する曲げ強度で、杭頭連結構造２０を構築する際に必要な補強鉄筋８の数を算定する。ここでは、例えば、曲げモーメントを、１５８０ｋＮ・ｍとする。
【００１６】
基礎コンクリート３２を、ＦＣ２４（圧縮強度２４Ｎ／ｍｍ^２）とし、補強鉄筋８としてＳＤ３９０（降伏強度３９０Ｎ／ｍｍ^２）を採用した場合、Ｄ_２寸法を変えた場合の補強鉄筋８の必要本数、その本数の場合の隣接する補強鉄筋８の間隔Ｄ_６は、下記表１の通りである。
【００１７】
杭頭に位置する既製杭としてもとしても、曲げモーメントの大きいＳＣ杭を使用した場合、ほぼ同様の曲げモーメントを得ることができる。
【００１８】
【表１】

【００１９】
表１において、Ｄ_２＝７００ｍｍの場合が従来例の場合である。従って、鉛直支持力が従来比約２倍で、使用されても曲げモーメントとしても容易に増強できることが分かる。
【００２０】
（３）従って、補強鉄筋８をＳＤ３９０として、長さＬ＝９００〜１１００ｍｍ程度、とすれば、補強鉄筋８を
Ｄ_２＝（既製杭１２の外径Ｄ_１１）＋３００ｍｍ
程度で形成すれば、補強鉄筋の本数が約２分の１で、必要な強度を満たすことができる。また、この場合、補強鉄筋８、８の間隔を４倍以上に広げることができる。
【００２１】
【実施例１】
図１、図２に基づきこの発明の実施例を説明する。
【００２２】
（１）杭頭補強具１０の構成
【００２３】
内径Ｄ_０、外径Ｄ_１の円盤状の基板（基部）１の外周２側に、外径Ｄ_２（Ｄ_２＞Ｄ_１１）の円周に沿って、鉄筋固定用の透孔４、４をほぼ等間隔で並列して形成する。基板１の下面に、透孔４に連通するナット５を固定する。基板１の内周３に沿って、適用する既製杭１２の上端板１４の上面の螺孔１５、１５に対応する透孔６、６を複数箇所に形成する。
【００２４】
透孔６に、下端部外周に螺糸を形成した補強鉄筋８を上方から、挿入して、ナット５にねじ込み、固定する。総ての透孔６、６に補強鉄筋８、８を固定すれば、補強鉄筋８、８は、基板１の上方に長さＬだけ突出し、かつ径Ｄ_２の円周に沿って等間隔に並列して配置される。
【００２５】
以上のようにして、杭頭補強具１０を構成する（図１（ａ）（ｂ））。図中３１は杭穴である。
【００２６】
前記において、

の場合、杭頭補強具１０は、例えば、
Ｄ_０＝７００ｍｍ
Ｄ_１＝１１００ｍｍ
Ｄ_２＝１０００ｍｍ
で形成し、また、補強鉄筋８は、
Ｌ＝１１００ｍｍ
外径φ＝２９ｍｍ
本数２３
で形成する。
【００２７】
従って、Ｄ_２を拡大することにより補強鉄筋８の本数を半分以下に低減している。
【００２８】
（２）杭頭結合構造２０
【００２９】
内径Ｄ_００、外径Ｄ_１１の既製杭１２を従来の方法により埋設し、杭頭部１３を地上に露出させる。既製杭１２を埋設する方法は、予め杭穴３１を掘削した後に既製杭１２を沈設する先掘工法、既製杭１２の下方で掘削しながら既製杭１２を徐々に沈設する中掘工法、打撃や回転により既製杭１２を押し込む工法等いずれの工法を適用しても可能である。
【００３０】
続いて、既製杭１２の上端板１４に、杭頭補強具１０の基板１の下面を載置し、透孔６と上端板１４に形成されている螺孔１５とを一致させる。透孔６から螺孔１５に向けてボルト１９を螺合緊結して、基板１と上端板１４とを固定すれば、既製杭１２に杭頭補強具１０が一体に固定される。
【００３１】
次に、建造物（上部構造部物）の基礎用の型枠、基礎用の鉄筋を構築し、必要ならば、基礎用の鉄筋と補強鉄筋とを接合する（図示していない）。
【００３２】
続いて、型枠内に基礎用コンクリート３２を打設すれば、杭頭補強具１０と既製杭１２の杭頭部１３とがコンクリート３２内に一体に埋設された杭頭結合構造２０を構築する（図２）。
【００３３】
（３）他の実施例
【００３４】
前記実施例において、補強鉄筋８は、基板１にボルト・ナットで螺合緊結したが、固定する手段は任意である。例えば、溶接で固定することもできる。
【００３５】
また、前記実施例において、補強鉄筋８は、予め固定したが、既製杭１２に基板１を固定した後に取り付けることもできる（図示していない）。
【００３６】
また、前記実施例において、既製杭１２の埋設後に杭頭補強具１０を取り付けたが、予め既製杭１２の上端板１４に杭頭補強具１０を固定した状態で、既製杭１２を埋設することもできる（図示していない）。
【００３７】
【実施例２】
図３〜図５に基づきこの発明の実施例を説明する。
【００３８】
（１）杭頭補強具１０の構成
【００３９】
外径Ｄ_４で、上方に開いた上筒２２は、径Ｄ_０の開口（円形）２５が形成されている底板２４を有する。上筒２２の底板２４に、内径Ｄ_５の下筒２６の上端を同軸に連設する。下筒２６の内径Ｄ_５は、使用する既製杭１２の外径Ｄ_１１と略同一に形成され、下筒２６が既製杭１２の杭頭部（上端板１４）１３に嵌装できるようになっている。また、上筒２２の開口２５の径Ｄ_０は、使用する既製杭１２の内径Ｄ_００と略同一に形成され、既製杭１２の中空部に連通できるようになっている。
【００４０】
また、底板２４に、既製杭１２の上端板１４の螺孔１５、１５と連通できる透孔６、６を穿設する。以上のようにして、基部２８を形成する。
【００４１】
基部２８の上筒２２の側板２３の外面に、縦に配置した補強鉄筋８、８の下端部を溶接して固定する。補強鉄筋８は、底板２４の上面から上方に長さＬだけ突出し、径Ｄ_２の円に沿って（外径Ｄ_４の上筒の外周に沿って）等間隔（間隔Ｄ_６）に並列して配置される。以上のようにして、杭頭補強具１０を構成する（図３（ａ）（ｂ））。
【００４２】
前記において、

の場合、杭頭補強具１０は、例えば、
Ｄ_０＝５６０ｍｍ
Ｄ_２＝１１００ｍｍ
で形成し、また、補強鉄筋８は、
Ｌ＝１１００ｍｍ
外径φ＝２９ｍｍ
本数２５
で形成する。補強鉄筋を並べた円の径Ｄ_２＝杭径Ｄ_１１＋３００ｍｍ程度とすることにより、補強鉄筋の本数を半分以下に削減できる（表１参照）。
【００４３】
（２）杭頭結合構造２０
【００４４】
実施例１と同様に、内径Ｄ_００、外径Ｄ_１１の既製杭１２を従来の方法により埋設し、杭頭部１３を地上に露出させる。
【００４５】
続いて、既製杭１２の上端板１４に、杭頭補強具１０の基部２８の底板２４を載置し、上筒２２の底板２４の透孔６、６と上端板１４の螺孔１５、１５を一致させる。透孔６から螺孔１５に向けてボルト１９を螺合緊結して、基部２８と上端板１４とを固定し、既製杭１２に杭頭補強具１０を一体に固定する（図４）。尚、図中１６は、上端板に連設された補強筒である。
【００４６】
次に、前記実施例１と同様に、建造物（上部構造部物）の基礎用の型枠、基礎用の鉄筋を構築し（図示していない）、必要ならば、基礎用の鉄筋と補強鉄筋８、８とを接合する。
【００４７】
続いて、型枠内に基礎用のコンクリート３２を打設すれば、杭頭補強具１０と既製杭１２の杭頭部１３とがコンクリート３２内に一体に埋設された杭頭結合構造２０を構築する（図４）。
【００４８】
（３）他の実施例
【００４９】
また、前記実施例において、上筒２２の外面に、補強鉄筋８、８を入れる位置に予め、補強鉄筋８を嵌挿できる凹部を形成しておくこともできる（図示していない）。この場合には、溶接の位置合わせが容易である。
【００５０】
また、前記実施例において、下筒２６を既製杭１２の上端板１４に嵌装させたが、下筒２６を既製杭１２の上端板１４の内側１８に嵌挿することもできる（図５（ａ））。更に、前記実施例において、下筒２６を省略することもできる（図５（ｂ））。これらの場合も同様に、基部２８の底板２４に上端板１４の螺孔１５に対応した透孔６、６を穿設しておき、透孔６からボルト１９をねじ込んで既製杭１２と杭頭補強具１０とを固定する（図５（ａ）（ｂ））。
【００５１】
【発明の効果】
（１）この発明では、既製杭の上端板に固定する基部に、補強鉄筋を固定したので、基部を大径とすれば、既製杭の外径より大径の位置で補強鉄筋を突設することができ、基礎用のコンクリート強度を適宜に設定すれば、隣接する補強鉄筋の間隔を適正化して、補強鉄筋の使用本数を大幅に削減できる。この場合、補強鉄筋の使用本数を半減させることがが可能であり、杭頭補強具の製造コスト、製造工数、総じて、杭頭連結構造のコスト削減、施工期間の短縮の効果が期待できる。
【００５２】
（２）また、前記のように、基礎用のコンクリート強度を適宜に設定し、接合筋間隔の適正化することにより、使用する補強鉄筋の長さを短くでき、総じて、構築される基礎を小型化できる効果がある。
【００５３】
（３）また、杭頭補強具と基礎杭の上端板とをボルトで接合できるので、接合品質が安定化し、接合作業者も習熟が容易となり、施工が確実かつ均一化し、施工期間が短縮できる効果がある。また、補強鉄筋の間隔が広いので、接合作業も容易となる。
【００５４】
（４）基礎用のコンクリートの強度、補強鉄筋の強度及び太さ、長さ、本数などを適正化することにより、構築される基礎の強度を高めることができると共に、基礎のの増減も容易に調節でき、求める建築物に応じて、所望強度の基礎を容易に構築できる効果がある。隣接する補強鉄筋の間隔を容易に２倍以上に拡げることができるので、補強鉄筋の太さを例えば２倍にして、基礎の強度を増強するすることも容易である。
【００５５】
（５）補強鉄筋間隔を従来に比して４倍以上に拡大できることにより、杭頭部に形成する建築構造物用の生コンクリートの骨材の粒径の選定範囲に制約を受けず、任意の骨材を選定できる効果がある。
【図面の簡単な説明】
【図１】この発明の実施例１に使用する杭頭補強具で、（ａ）は平面図、（ｂ）は（ａ）のＡ−Ａ線における断面図である。
【図２】この発明の杭頭連結構造の縦断面図である。
【図３】この発明の実施例２に使用する他の杭頭補強具で、（ａ）は平面図、（ｂ）は（ａ）のＢ−Ｂ線における断面図である。
【図４】この発明の他の杭頭連結構造の縦断面図である。
【図５】（ａ）（ｂ）は、この発明の実施例２に使用する他の杭頭補強具の一部拡大図である。
【符号の説明】
１基板（基部）
２基板の外周
３基板の内周
４透孔（補強鉄筋用）
５ナット
６透孔（端板固定用）
８補強鉄筋
１０杭頭補強具
１２既製杭
１３既製杭の杭頭部
１４既製杭の上端板
１５既製杭の螺孔（上端板の上面）
１９ボルト
２０杭頭連結構造
２２上筒
２６下筒
２７下筒の透孔
２８基部
３１杭穴
３２基礎のコンクリート[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pile head connection structure of a ready-made pile for connecting a pile head of a ready-made pile and a foundation as a lower end of a building. This simplifies the joint structure between the pile head of the ready-made pile and the foundation, simplifies the joint work on site, and can strengthen the joint strength of the pile head without lowering it. Therefore, the load capacity per pile foundation has been improved nearly twice as much as before by forming the enlarged diameter part with the high quality soil cement layer or the rooting part in the pile foundation which has been recently implemented. A pile foundation using a concrete pile having a high bearing capacity is particularly effective because the strength of the bending moment required for the foundation is large.
[0002]
[Prior art]
In the conventional foundation, generally, the upper end plate of the ready-made pile was removed, the concrete at the upper end was broken to expose the shaft reinforcing bar, and the reinforcing bar arranged on the foundation was welded to the shaft reinforcing bar. Further, a structure in which a lower portion of a reinforcing bar is inserted into a hollow portion of a pile head of a ready-made pile as a reinforcing reinforcing bar, and a contact is filled and fixed is provided (a conventional example described in Patent Document 1; FIG. 7 of Patent Document 1). And Fig. 8. Non-patent document 1).
[0003]
Therefore, a structure that surrounds the pile head of a ready-made pile with a cylindrical lower cage-like connecting bar or welds a connecting bar to the pile head and attaches it to the ground to build a structural body (foundation) has been developed. It has been proposed (Patent Document 1).
[0004]
[Patent Document 1]
JP-A-11-21915 [0005]
[Non-patent document 1]
"From Survey / Design of Pile Foundation to Construction", 2nd revised edition, Japan Society of Geotechnical Engineers, May 25, 1993, pp. 214-220 [0006]
[Problems to be solved by the invention]
Recently, the load-bearing capacity of one pile has been improved, and in particular, a concrete-made pile has been put to practical use with a high bearing capacity of about twice as large as the conventional pile diameter. (Bending moment) to increase the strength of the building as a whole.
[0007]
In this case, in the conventional technique, there is a limit in increasing the number of adjacent reinforcing bars from the viewpoint of securing the cover of the reinforcing bars, and when the thickness of the reinforcing bars is increased, the weight of one bar increases. In addition, handling such as transportation is troublesome, and there is a problem that it is difficult to hold a reinforcing bar and obtain a predetermined strength in the field welding work itself.
[0008]
In addition, under the restriction of the reinforcing steel, there is a problem that the concrete for the foundation has to adopt a special concrete having higher strength than that used for the frame of the ordinary building structure.
[0009]
That is, the conventional technique has the following problems.
(1) At the pile head of the pile foundation, the spacing of the joint reinforcement in the foundation concrete is narrow, and the strength of each of the concrete and joint (fixation) bars is not fully utilized. The unity was not good. For this reason, the bending strength as a base was low for the strength of the material used. In the foundation, the arrangement (arrangement) of the joint bars in the concrete was too close, and the balance between the concrete strength and the joint (anchoring) bar was poor, and the enhancement of the bending moment at the joint was limited.
(2) The joining work of the joining (fixing) studs and the pile head is complicated and requires experience, so it is troublesome to maintain the stability of joining quality and the proficiency of joining operators.
(3) Due to the factors of (1) and (2), the cost of materials and work is increased to create the foundation pile and foundation concrete. In addition, when the number of welding points is large, the welding work depends on the weather. Therefore, it has become one of the factors that hinder the further reduction of the number of working days.
[0010]
[Means for Solving the Problems]
However, according to the present invention, the above-mentioned problem is solved because the pile head reinforcement having the reinforcing bar projecting circumferentially with a diameter larger than the outer diameter of the pile is fixed to the pile end plate of the ready-made pile.
[0011]
That is, the present invention has a structure in which a base of a pile head reinforcing device is fixed to an upper end plate of a ready-made pile with a pile head exposed, and a base having an opening communicating with a hollow portion of the ready-made pile, A pile head connecting structure for a ready-made pile, wherein a reinforcing bar is projected from a position larger in diameter than the outer diameter of the ready-made pile to constitute the pile head reinforcing tool.
[0012]
Also, in the above, a donut-shaped base having an opening whose outer periphery is larger than the outer diameter of the ready-made pile and whose inner periphery is substantially the same as the inner diameter of the ready-made pile is formed, and reinforced along the outer periphery of the base. A pile head reinforcement is constructed by projecting reinforcing bars side by side in an upward direction, and the base and the ready-made pile are connected to each other by using a through hole formed in the base and a screw hole of an upper end plate of the ready-made pile. It is a pile head connection structure characterized by being fixed. In addition, a bottom plate having an opening substantially the same as the inner periphery of the ready-made pile is formed in an upper cylinder having an outer diameter larger than the outer diameter of the ready-made pile, and the bottom plate is used as a base. Are piled up in parallel to form a pile head reinforcing device.
[0013]
Further, in the above, the pile head reinforcing member and the ready-made pile are fixed using a through hole formed in a base portion and a screw hole formed in an upper end plate of the ready-made pile. It is a reinforcement structure.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
(1) The pile head 13 is exposed on the ground, and the ready-made pile 12 is laid. The pile head reinforcement 10 having the reinforcing

steel bars

8, 8 projecting upward is fixed to the upper end plate 14 of the ready-made pile 12 (FIG. 2). Reinforcing

rebar

8, 8 along the circumference of diameter D _2, it is fixed to the substrate 1 of the pile head brace 10 (Fig. 1). The substrate 1 is fixed to the upper end plate 14 of the ready-made pile 12 with

bolts

19, 19. Diameter D ₂ of the circle in parallel reinforcing rebar 8, by increasing the outer diameter D ₁ of the substrate 1 can be formed with a sufficiently large diameter D ₂ than the outer diameter D ₁₁ of the ready-made pile 12.
[0015]
(2) A case where the ready-made pile 12 (outer diameter D ₁₁ = 700 mm) is laid in the pile hole 31 in which the expanded bottom stiffened portion 1100φ is formed, and the foundation pile having a tip support force of about 20 N / mm ^2. Can be constructed. In this case, the number of reinforcing steel bars 8 required when constructing the pile head connection structure 20 is calculated with a bending strength corresponding to the high supporting force of the expanded bottom stiffened portion. Here, for example, the bending moment is 1580 kN · m.
[0016]
The concrete foundation 32, if the FC24 (compressive strength 24N / mm ^2), was employed SD390 (yield strength 390 N / mm ²⁾ as a reinforcing rebar 8, the necessary number of reinforcing rebar 8 when changing the _{D 2} dimension, the distance D ₆ between adjacent reinforcing rebar 8 when the number is shown in table 1 below.
[0017]
Even when an SC pile having a large bending moment is used as a ready-made pile located at the pile head, almost the same bending moment can be obtained.
[0018]
[Table 1]

[0019]
In Table 1, the case where D ₂ = 700 mm is the case of the conventional example. Therefore, it can be seen that the vertical supporting force is about twice that of the conventional art, and that the bending moment can be easily increased even when used.
[0020]
(3) Accordingly, the reinforcing rebar 8 as SD390, if the length L = 900~1100mm about, and, the reinforcing rebar 8 _D 2 = (outer diameter _D 11 of the ready-made pile 12) + 300 mm
If it is formed in such a degree, the number of reinforcing bars can be reduced to about one half and the required strength can be satisfied. Further, in this case, the interval between the reinforcing reinforcing

bars

8, 8 can be increased four times or more.
[0021]
Embodiment 1
An embodiment of the present invention will be described with reference to FIGS.
[0022]
(1) Configuration of Pile Head Reinforcement 10
On the outer periphery 2 side of a disk-shaped substrate (base) 1 having an inner diameter D ₀ and an outer diameter D ₁ , along the circumference of an outer diameter D ₂ (D ₂ > D ₁₁ ), through

holes

4, 4 for fixing reinforcing steel. Are formed in parallel at substantially equal intervals. A nut 5 communicating with the through hole 4 is fixed to the lower surface of the substrate 1. A plurality of through

holes

6, 6 corresponding to the screw holes 15, 15 on the upper surface of the upper end plate 14 of the ready-made stake 12 to be applied are formed along the inner periphery 3 of the substrate 1.
[0024]
A reinforcing reinforcing bar 8 having a thread formed on the outer periphery of the lower end portion is inserted into the through hole 6 from above, screwed into the nut 5 and fixed. It is fixed to the reinforcing

rebar

8,8 to all through

holes

6,6, reinforcing

rebar

8, 8 by a length L over the substrate 1 projects, and at equal intervals along the circumference of the diameter D ₂ They are arranged in parallel.
[0025]
The pile head reinforcement 10 is configured as described above (FIGS. 1A and 1B). In the figure, reference numeral 31 denotes a pile hole.
[0026]
In the above,

In the case of, the pile head reinforcement 10 is, for example,
D ₀ = 700 mm
D ₁ = 1100 mm
D ₂ = 1000 mm
And the reinforcing bar 8 is
L = 1100mm
Outer diameter φ = 29mm
Number 23
Formed.
[0027]
Therefore, it is reduced to less than half the number of reinforcing rebar 8 by enlarging the D _2.
[0028]
(2) Pile head connection structure 20
[0029]
A ready-made pile 12 having an inner diameter D ₀₀ and an outer diameter D ₁₁ is buried by a conventional method, and a pile head 13 is exposed on the ground. The method of burying the ready-made pile 12 is a pre-digging method in which the pile hole 31 is excavated in advance and then digging the ready-made pile 12, a digging method in which the ready-made pile 12 is gradually laid while excavating below the ready-made pile 12, a hitting method, It is possible to apply any construction method such as a construction method of pushing the ready-made pile 12 by rotation.
[0030]
Subsequently, the lower surface of the substrate 1 of the pile head reinforcing device 10 is placed on the upper end plate 14 of the ready-made pile 12, and the through hole 6 and the screw hole 15 formed in the upper end plate 14 are aligned. When the bolt 19 is screwed and tightened from the through hole 6 to the screw hole 15 to fix the substrate 1 and the upper end plate 14, the pile head reinforcement 10 is integrally fixed to the ready-made pile 12.
[0031]
Next, a formwork for the foundation of the building (superstructure) and a reinforcing steel for the foundation are constructed, and if necessary, the reinforcing steel for the foundation and the reinforcing steel are joined (not shown).
[0032]
Subsequently, if the foundation concrete 32 is poured into the formwork, the pile head connecting structure 20 is constructed in which the pile head reinforcement 10 and the pile head 13 of the ready-made pile 12 are integrally embedded in the concrete 32. (FIG. 2).
[0033]
(3) Another embodiment
In the above-described embodiment, the reinforcing reinforcing bar 8 is screwed and tightened to the substrate 1 with bolts and nuts. For example, it can be fixed by welding.
[0035]
In addition, in the above-described embodiment, the reinforcing reinforcing bar 8 is fixed in advance, but may be attached after fixing the substrate 1 to the ready-made pile 12 (not shown).
[0036]
Further, in the above-described embodiment, the pile head reinforcing device 10 is attached after the ready-made pile 12 is buried, but the ready-made pile 12 is buried in a state where the pile head reinforcing device 10 is fixed to the upper end plate 14 of the ready-made pile 12 in advance. (Not shown).
[0037]
Embodiment 2
An embodiment of the present invention will be described with reference to FIGS.
[0038]
(1) Configuration of Pile Head Reinforcement 10
An outer diameter D _4, upper cylinder 22 open upward has a bottom plate 24 which opening (round) 25 is formed in the diameter D _0. The bottom plate 24 of the upper cylinder 22, is continuously provided to the upper end of the lower tubular 26 having an inner diameter D ₅ coaxially. The inner diameter D ₅ of the lower tubular 26 is substantially equal to the outside diameter D ₁₁ of the prefabricated pile 12 to be used, so the lower tube 26 can be fitted to the pile head (upper plate 14) 13 of the ready-made pile 12 ing. Further, the diameter D ₀ of the opening 25 of the upper cylinder 22 is formed to be substantially the same as the inner diameter D ₀₀ of the ready-made pile 12 to be used, and can communicate with the hollow portion of the ready-made pile 12.
[0040]
Further, in the bottom plate 24, through

holes

6, 6 that can communicate with the screw holes 15, 15 of the upper end plate 14 of the ready-made pile 12 are formed. The base 28 is formed as described above.
[0041]
The lower ends of the reinforcing reinforcing

bars

8, 8 arranged vertically are fixed to the outer surface of the side plate 23 of the upper cylinder 22 of the base 28 by welding. The reinforcing bars 8 protrude upward from the upper surface of the bottom plate 24 by a length L and are arranged in parallel at regular intervals (interval D ₆ ) along a circle having a diameter D ₂ (along the outer periphery of the upper cylinder of the outer diameter D ₄ ). Placed. The pile head reinforcing device 10 is configured as described above (FIGS. 3A and 3B).
[0042]
In the above,

In the case of, the pile head reinforcement 10 is, for example,
D ₀ = 560 mm
D ₂ = 1100 mm
And the reinforcing bar 8 is
L = 1100mm
Outer diameter φ = 29mm
Number 25
Formed. By the diameter _{D 2} = pile diameter _D 11 + 300 mm approximately circle arranged reinforcement rebar, it is possible to reduce the number of reinforcing rebar to less than half (see Table 1).
[0043]
(2) Pile head connection structure 20
[0044]
As in the first embodiment, a ready-made pile 12 having an inner diameter D ₀₀ and an outer diameter D ₁₁ is buried by a conventional method, and a pile head 13 is exposed on the ground.
[0045]
Subsequently, the bottom plate 24 of the base 28 of the pile head reinforcement 10 is placed on the upper end plate 14 of the ready-made pile 12, and the through

holes

6, 6 of the bottom plate 24 of the upper cylinder 22 and the screw holes 15, 15 of the upper end plate 14 are placed. To match. A bolt 19 is screwed and tightened from the through hole 6 to the screw hole 15 to fix the base 28 and the upper end plate 14, and the pile head reinforcement 10 is integrally fixed to the ready-made pile 12 (FIG. 4). In the figure, reference numeral 16 denotes a reinforcing cylinder connected to the upper end plate.
[0046]
Next, in the same manner as in the first embodiment, a formwork for the foundation of the building (superstructure) and a reinforcing bar for the foundation are constructed (not shown). The reinforcing

bars

8, 8 are joined.
[0047]
Subsequently, if the concrete 32 for foundation is poured into the formwork, the pile head connecting structure 20 in which the pile head reinforcing tool 10 and the pile head 13 of the ready-made pile 12 are integrally buried in the concrete 32 is constructed. (FIG. 4).
[0048]
(3) Another embodiment
Further, in the above-described embodiment, a concave portion (not shown) in which the reinforcing bar 8 can be inserted may be formed in advance on the outer surface of the upper cylinder 22 at a position where the reinforcing bar 8 is to be inserted. In this case, welding positioning is easy.
[0050]
Further, in the above-described embodiment, the lower cylinder 26 is fitted to the upper end plate 14 of the ready-made pile 12, but the lower cylinder 26 can be fitted to the inner side 18 of the upper end plate 14 of the ready-made pile 12 (see FIG. a)). Further, in the above embodiment, the lower cylinder 26 may be omitted (FIG. 5B). Similarly, in these cases, through

holes

6, 6 corresponding to the screw holes 15 of the upper end plate 14 are drilled in the bottom plate 24 of the base 28, and bolts 19 are screwed from the through holes 6 to make the ready-made pile 12 and the pile head 12. The reinforcement 10 is fixed (FIGS. 5A and 5B).
[0051]
【The invention's effect】
(1) In the present invention, since the reinforcing bar is fixed to the base fixed to the upper end plate of the ready-made pile, if the base has a large diameter, the reinforcing bar protrudes at a position larger in diameter than the outer diameter of the ready-made pile. If the concrete strength for the foundation is set appropriately, the spacing between adjacent reinforcing bars can be optimized, and the number of reinforcing bars used can be greatly reduced. In this case, it is possible to reduce the number of reinforcing bars used by half, and it can be expected that the production cost and the number of man-hours for the pile head reinforcing tool, and in general, the cost reduction of the pile head connection structure and the effect of shortening the construction period can be expected.
[0052]
(2) Also, as described above, by appropriately setting the concrete strength for the foundation and optimizing the joint bar spacing, it is possible to shorten the length of the reinforcing steel bar to be used. There is an effect that can be converted.
[0053]
(3) In addition, since the pile head reinforcement and the upper end plate of the foundation pile can be joined by bolts, the joining quality is stabilized, the joining operator becomes easy to learn, the construction is reliable and uniform, and the construction period can be shortened. effective. In addition, since the interval between the reinforcing bars is wide, the joining operation is also facilitated.
[0054]
(4) By optimizing the strength of concrete for the foundation, the strength and the thickness, length, and number of reinforcing bars, the strength of the constructed foundation can be increased, and the increase and decrease of the foundation can be easily performed. There is the effect that it can be adjusted and the foundation of the desired strength can be easily constructed according to the desired building. Since the interval between adjacent reinforcing bars can be easily expanded to twice or more, it is easy to increase the strength of the foundation by, for example, doubling the thickness of the reinforcing bars.
[0055]
(5) Since the spacing between the reinforcing steel bars can be increased four times or more as compared with the conventional method, the selection range of the particle size of the aggregate of the ready-mixed concrete for the building structure formed at the pile head is not limited, and any arbitrary size can be obtained. There is an effect that an aggregate can be selected.
[Brief description of the drawings]
1A and 1B are pile head reinforcements used in Embodiment 1 of the present invention, wherein FIG. 1A is a plan view and FIG. 1B is a cross-sectional view taken along line AA of FIG.
FIG. 2 is a vertical sectional view of a pile head connection structure of the present invention.
3 (a) is a plan view, and FIG. 3 (b) is a cross-sectional view taken along line BB of FIG. 3 (a).
FIG. 4 is a longitudinal sectional view of another pile head connection structure of the present invention.
FIGS. 5 (a) and 5 (b) are partially enlarged views of another pile head reinforcing tool used in Embodiment 2 of the present invention.
[Explanation of symbols]
1 substrate (base)
2 Outer perimeter of substrate 3 Inner perimeter of substrate 4 Through-hole (for reinforcing steel)
5 Nut 6 Through hole (for fixing end plate)
8 Reinforcing Bar 10 Pile Head Reinforcement 12 Ready Made Pile 13 Ready Made Pile Head 14 Ready Made Pile Upper End Plate 15 Ready Made Pile Screw Hole (Top Surface of Upper End Plate)
19 bolt 20 pile head connection structure 22 upper cylinder 26 lower cylinder 27 lower cylinder through-hole 28 base 31 pile hole 32 foundation concrete

Claims

A structure in which the base of the pile head reinforcement is fixed to the upper end plate of the ready-made pile with the pile head exposed,
A prefabricated pile characterized by comprising a reinforcing bar projecting from a base having an opening communicating with a hollow portion of the prefabricated pile at a position larger in diameter than the outer diameter of the prefabricated pile to constitute the pile head reinforcing tool. Pile head connection structure.

The outer periphery is larger in diameter than the outer diameter of the ready-made pile, and the inner periphery is formed as a donut-shaped base having an opening substantially the same as the inner diameter of the ready-made pile, and the reinforcing bar is directed upward along the outer periphery of the base. To protrude in parallel to form a pile head reinforcement,
The pile head coupling structure according to claim 1, wherein the base and the ready-made pile are fixed using a through hole formed in the base and a screw hole of an upper end plate of the ready-made pile.

A bottom plate having an opening substantially the same as the inner periphery of the ready-made pile is formed in an upper cylinder having an outer diameter larger than the outer diameter of the ready-made pile, and a reinforcing bar is formed on a side surface of the upper cylinder with a reinforcing bar. The pile head reinforcement structure according to claim 1, characterized in that the pile head reinforcement is formed by projecting in parallel to the pile head.

The said pile head reinforcement and the said ready-made pile were fixed using the through-hole formed in the base part, and the screw hole formed in the upper end plate of the ready-made pile. The Claim 1 thru | or 3 characterized by the above-mentioned. The pile head reinforcement structure according to any one of the above items.